Planar fluorescent lamps are useful in many applications, including backlights for liquid crystal displays (LCDs). A conventional planar fluorescent lamp 900 includes a spacer (not shown), a front glass plate 942 coated with a first fluorescent layer 952, and a rear glass plate 944 coated with a second fluorescent layer 954 to form a channel 930, as shown in FIG. 9. The planar fluorescent lamp 900 also includes four electrodes 912, 913, 914 and 915, where the electrodes 912 and 914 are positioned over a first end and a second end of the front glass plate 942, respectively, and the electrodes 913 and 915 are positioned over a first end and a second end of the rear glass plate 944, respectively. In operation, the planar fluorescent lamp 900 is driven by a high voltage applying to the electrodes 912-915 such that electric discharging is generated through the front glass plate 942 and the rear glass plate 944 to excite the fluorescent layers 952 and 954, and the channel 930 emits light.
FIG. 8 shows an effective circuit 800 of a conventional planar fluorescent lamp. In such a planar fluorescent lamp, glass plates contacted by electrodes can effectively be accounted as capacitors 812 and 814 having an effective capacitance C =∈A/d, where ∈ is the dielectric constant of the glass plates, d is the thickness of the glass plates, and A is the contact area of the electrodes with the fluorescent channel (tube) 820. The planar fluorescent lamp is powered by an inverter 840. The relationship of the impedance Xc of the lamp channel 820 and the effective capacitance C is determined by Xc=1/(jωC), wherein j is the imaginary number and ω is the frequency of the current passing through the lamp channel 820. Accordingly, decreasing the effective capacitance C results in increasing the impedance Xc.
It is known in the art that the thinner a channel (lamp tube) is, the higher the light emission efficiency of the channel (lamp tube) is. As shown in FIG. 10, a conventional planar fluorescent lamp 1000 usually utilizes a plurality of thin and uniform channels 1020 formed substantially in parallel to improve its light intensity and quality, where each of the plurality of thin and uniform channels 1020 has a width, Ac, and is contacted with two electrodes 1012 and 1014, each having a width, Ae. The electrode contact area of a channel 1020 with the electrode 1012 (1014) is determined by (Ac×Ae). However, a conventionally thin channel means that the channel has a small, uniform width, and thus a small electrode contact area results in a small effective capacitance thereof. When the effective capacitance decreases, the impedance of the channel increases accordingly, thereby resulting in the increase of the operating voltage of the channel and the decrease of the channel current. The former may result in the generation of ozone and pin-holes in the channel and the latter may produce an insufficient amount of light and reduce the light emission efficiency of the channel.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.